Metallurgical furnace



Jan. 7, 1930. F, A. J. FITZGERALD ET AL 1,742,441

METALLURGI CAL FURNACE Filed July 24, 1928 firron IVE) mated Jan. 1,1930 UNITED STATES PATENT OFFICE FRANCIS A. J. FITZGERALD, OI NIAGARAFALLS, NEW YORK, AND JAMES KELLEKEB, OF CHIPIPEWA, ONTARIO, CANADA,ASSIGNORS 'IO TITANIA CORPORATION, OF L08 AN GELES, CALIFORNIA,

A CORPORATION 01' CALIFORNIA mz'mmoaercan summon Application filed July24, 1928. Serial No. 834,981.

7 It is well known to those skilled in the art that certain combinationsof titanium oxide and carbon when subjected to heat in an atmosphere ofnitrogen gas reacts toform carbon monoxide and titanium nitride, asclearly set forth'in the United States Patents Nos. 1,391,147 and1,391,148, issued September 20, 1921 to Bichowsky, et al.

The materials to be treated by our 1nven-. tion consist of titanium oremixed with carbon and a suitable catalyst, such as sodium carbonate, asset forth in the Bichowsky patents. This material is ground to anextremely fine powder and mixed with some organic bond, such as glucoseor molasses, after which it is briquetted so as to form a suitablecharge for a furnace. One of the common'methods of reducing such acharge is to place 1t In a shaft furnace, using coke as fuel, as forexample the reduction of iron ores in a blast furnace. However, in theprocess for WhlCh our invention is desi ned, a fuel-fired furnace cannot be usedfor eating the briquettes to the desired temperature, becausethe reaction will not take lace except in an oxygen; free atmosphere.l3ecause of this reason it is essential that electric furnaces be emploed,

but an electric furnace with the usual s aft is not only difficult tocontrol, but has a great many other objections, because of scaffolding,explosions, and the like.

The principal object of our 1nvent1on has been to provide a furnace 1nwhich the process described in the Bichowsky et alpatent referred to maybe practiced in a continuous manner for the production oftltamum-nltrogen compounds.

Another object has been to provide a furnace in which the temperature ofthe reacting mass may be accurately controlled.

A further object has been to provide a furnace having heating meansWfllldt shall uniformly heat the charge contained 1n the fur-.

nace.

Moreover, our furnace is provided w th means for protecting the ,fimshedmaterial from oxidation and for removing it from the furnace withoutnitrogen gas. 7 p v Furthermore, our furnace provides means permittingthe escape of the roof 20, is a gate for preheating the nitrogen gas,and the untreated charge, and for recovering the combustible gasesgenerated by the reaction.

The furnace hereinafter described attains the objects above recited andovercomes the disadvantages hereinbefore pointed out, and ishshplwn inthe accompanying drawings, of w 10 Fig. 1 is a transverse, sectionalelevation of our u made of steel and having its joints welded so 66 asto prevent the leakage of gas. The shell comprises a front wall 6, arear wall 7, and end walls 8 and 9. A bottom 10 extends inwardly fromthe front wall 6 and a bottom 11 extends inwardly from the rear wall 7.The 70 front wall 6 is provided with a lining 14, and the rear wall Theend walls 8 and 9 also have linings 16 and 17, respectively. Theselinings are made of refractory bricks of a type suitable temperatures ofbetween 1400 and 1500 C. The roof of the furnace comprises preferably aplate 20 which is made of .graphite and may be supported by the linings14, 16 and 17. This plate is preferably so removable. The top of thefurnace and the roof 20 is covered with a layer 21 of suitable firebrick, carborundum fire sand, or the like.

Formed lengthwise in the top of the furnace, near the rear wall 7thereof tudinal charging hopper 22. A plate 23 serves to cover thehopper during the operation of the device. The lining 15 is wider nearits bottom than it is near its top and an inclined surface portions ofthe lining, whereby a chute 18 is formed between the hopper 22 and thechamber 24 for conducting the briquettes into'the furnace chamber 24.Arranged immediately above this chute,

25 which may also be of graphite and which orovides a fixed opening 26at the end of the chute 18. k Arranged at the bottom of the chamber 24and connecting the bottoms 10 and 11 is an inmace, and is taken online'11 of to 7 is provided with a lining 15. 4 r

to stand ranged thatit is is a longijoins the upper and lower andpreferably under the clined grate 30, comprising a stationary member 31which may be welded to the bottoms 8 and 9 of the furnace shell. Amovable member 32 is slidably carried by the stationary member 31 and isheld in place preferably by means of the overhanging lips 33 of thestationarymember. A shaker rod 34 is attached to the movable member andpasses through the end furnace lining 17 and end wall 9 of the shell. Astufling box 35 is carried by the shell at the point Where the shakerrod passes therethrough so as to make a gas-tight joint. A shaker arm 36is carried by the wall and provides means whereby the grate may beshaken. The grate members 31 and 32 are preferably made of plates whichare provided with apertures 40 and 41, respectively. These apertures arebrought into registration by the movement of the movable grate member32. Vertically extending rods 42 are carried by the movable member, andare moved through the charge in the furnace when the movable member isoperated, whereby caking or crusting of the charge is prevented. Thegrate 30 is arranged at an angle which corresponds substantially to theangle of repose of thematerials being treated, so that an even thicknessof briquettes is maintained on the grate when the furnace is beingoperated, as indicated by the dotted line 43 in Fig. 1. Obviously anysuitable type of grate, other than that shown and above described may beemployed in our device.

A discharge hopper 44 is located beneath the furnace and connects thebottoms 10 and 11. It is provided atits lower end with some suitablemeans of permitting the finished product to be discharged therefromwithout permitting gas to escape during such discharge. For convenience,I have shown a r0- tatable valve 45 for accomplishing this end. Thisvalve is provided with an opening 46 running preferably its full lengthand with end walls 47. The valve is cylindrical in form and is mountedbetween suitable cylindricalsurfaces 48 formed at the mouth of thehopper 44. A discharge opening 49 is formed between the tops of thesurfaces 48 and a discharge opening 50 is formed between the bottoms ofsuch. surfaces. The proportion of the discharge openings 49 and 50, andthe opening 46 of the'valve are such, in relation to the length of thecylindrical surfaces 48. that upon rotation the discharge opening 49will be closed by the valve 45 before the opening 5 is opened by theregistration therewith of tl e opening 46; of the valve. The end walls 4of the valve are provided with shafts 51 which preferably pass throughstufiing boxes 52 carried bv the end walls 53 of the hopper, wherebyleakage of gas is prevented at these points. Any suitable means such asa crank .56 may be attached to one of the shafts 51 .for rotating thevalve.

The furnace is preferably supported some distance above the floor uponsuitable legs or braces 54 and 55.

Arranged in the chamber 24, above the charge contained therein, is anelectric resistor .60 which extends across the furnace and is held bytwo electrodes 61 and 62. These electrodes pass through the lining 14and wall 6 of the furnace and are connected in any well known way with asuitable source of electric current. An observation tube 64 is arrangedin the top of the furnace and passes through the layer 21 of insulatingmaterial and roof 20, having its lower end extending into the chamber24. This tube is made of any suitable material which will withstand hightemperatures and the action of carbon monoxide, such, for instance, asAcheson graphite. This tube is for the purpose of observing the rate ofreaction and the progress of the reaction in the briquettes.

The observing tube is preferably provided treatment by means of anysuitable tempera-.

ture indicating device, such as an optical pyrometer, thermocouple, ortotal radiation pyrometer.

Since the Bichowsky processes are carried out in the presence ofnitrogen I provide suitable means for supplying such gas to the interiorof the furnace These means comprise tubes 70, 71 and 72. The tubes and71 are preferably arranged in the chamber 24 and immediately over thegrate 30, so that the gas will pass up through the charge of briquettesdisposed upon the grate. The tube 7 2 is preferably arranged near thebottom of the discharge hopper 44. Each of these tubes may be formedwith a slot 7 3 or' suitable apertures may be provided if desired. I Theslots or apertures are arranged at the lowermost point of the tubes sothat they will not become clogged by the charge. By placing the tube 72near the bottom of the hopper, the ho per is thus filled with nitrogenga's, there y preventing any reversible action that might occur when thetitanium nitride is hot. The tubes may be formed of the ordinary iron orsteel piping, and they maybe suitably connected together, as shownthedrawings, and to a main supply pipe When carrying out the Bichowskyprocess by means of our device, the briquettes to be treated are fedinto the charging hopper 22 until it is full.

Because of the construction" and arrangement of the gate 25, the chamber24 will also be filled to approximately the level shown by the dottedline 43. Nitrogen 'gas is now introduced into the furnace through thetubes 70, 71 and 72 until the air in the furnace is completely displacedby nitrogen. The charging hopper is now closed by means of the cover 23and the observation tube 64 is also closed by means of the cap 65,whereby a sli ht internal pressure of the nitrogen gas is rought aboutand maintained within the furnace. The electric current is now switchedon and, after a few minutes, the load in the furnace is brought up toits maximum so as to permit the most rapid heating of the furnace andbriquettes. When the furnace temperature, as measured through thetemperature tube 66 reaches approxi mately l000t0 1100 (3., the streamof nitro gen is increased, since a slight reaction takes place even atthese temperatures. The rate' of reaction is determined by opening thetop of the observation tube 64 and observing the color of the flame andthe chemical composition of the gases. It has been found that theoptimum operating temperatures lie between 1100 and 1550 (l, and whenthe furnace has attained the desired temperature for optimum rate ofreaction, the required amount of nitrogen gas is permitted to enterthrough the tubes 70, 71 and 72. At this point the cover 23 of thecharging hopper 22 is removed,

ermitting the gases to pass through the riquettes in this hopper. Thegases passing out through the charging hopper and through theobservation tube 64 consist primarily of carbon monoxide, and nitrogenand react with any metallic oxides in the hopper 44, because thebriquettes at this point will have reached a sufficient temperature tobring about a reducing action in an atmosphere of carbon monoxide, andin this place in the furnace it has been found that all the iron oxidespresent in the titanium ore are reduced and that, also, a preliminarynitrification of the material takes place. he gases passing up throughthe hopper 22 maybe collected and used elsewhere, since they arecombustible, or else they may be burned directly at the opening'of thehopper. In the passageof these gases up through the hopper, the chargeof briquettes contained therein are preheated before they are chargedinto the chamber 24 of the furnace...

When the briquettes on the top of the grate 30 have been treated for therequired amount of time, the flame issued from the observation tube 64will be seen to go down. The grate 30 is then shaken a definite amount,whichawill cause some .of the treated briquettes to fall throughthe-openings 40 and 41 in the/grate members 31 and 32, respectively, andbe deposited in the discharge hopper 44. After these treated briquettesare passed through the grate, a thin layer of green bri- Since thedischarge hopper 44 is not pro- I vided with any refractory lining, itwill be seen that theheat contained in the finished briquettes as theyare passed through the grate 30 will be permitted to radiate. If theradiation is not rapid enough to cool off the finished briquettes in theallotted time, water may be used in the hopper for the purpose. Bycooling the briquettes before they are discharged through the valve 25,oxidation of the product is prevented.

The temperature of the briquettes, by means of our device may bemaintained within very close limits by adjusting the amount ofelectrical energy supplied to the resister 60, which is an essentialrequirement in the carrying out of the Bichowsky processes.

The amount of nitrogen gas fed to the furnace is depended upon the rateat which the briquettes are being treated, and the point at Which newbriquettes are to be fed into the furnace, which is indicated by theflame condition at the opening of the observation tube 641 Sincereaction does not take place until the nitrogen as reaches the top ofthe-charge, the gas will e preheated by the charge before it reaches thetop thereof.

Obviously, some modifications of the details herein shown and describedmay be made without departing from the spirit of my invention or thescope ofthe appended claims, and I do not,'therefore, wish to be limitedto the exact embodiment herein shown and described, the form shownbeing'merely a preferred embodiment thereof. 1

Having thus described our invention, what we claim is:

. 1. An electric furnace for the production of titanium-nitrogencompounds, comprising a ,Iefractory body forming a chamber, an in clinedgrate arranged at the bottom of the chamber for supporting the charge,and a radiant resistor. carried'by the body and arranged within thechamber some distance "above the charge.

charge, a charging hopper formed in the upper part of the body, and achute connecting the charging hopper with the chamber.

3. An electric furnace for the production of titanium-nitrogencompounds, comprising a refractory body forming a chamber, an inclinedgrate arranged at the bottom of the chamber for supporting the charge, aradiant resistor carried by the body and arranged within the chambersome distance above the charge, and means for admitting nitrogen gasinto the chamber.

'4. An electric furnace for the production of titanium-nitrogencompounds, comprising a refractory body forming a chamber, an inclinedgrate arranged at the bottom of the chamber, a radiant resistor carriedby the body and arranged within the chamber some distance above thegrate, a gas-tight discharge hopper arranged below the grate, and meansfor admitting nitrogen gas into the chamber and discharge hopper.

5. An electric furnace for the production of titanium-nitrogencompounds, comprising a refractory body forming a chamber, an inclinedgrate arranged at the bottom of the chamber, a radiant resistor carriedby the body and arranged within the chamber-some distance above thegrate, a charging hopper formed in the upper part of the body, a chuteconnecting the discharge hopper with the chamber, a gas-tight dischargehopper arranged below the grate and means for admitting nitro en gasinto the discharge hopper. 6. An e ectric furnace for the production oftitanium-nitrogen compounds, comprising a refractory body forming achamber, an inclined grate arranged at the bottom of the chamber forsupporting the charge, a radiant resistor carried by the body andarranged within the chamber some distance above the charge, a charginghopper formed in the upper part of the body, a chute connecting thecharging hopper with the chamber, and a gate carried by the body forlimiting the size of the chute.

7. An electric furnace for the production of titanium-nitrogencompounds, comprising a refractory body forming a chamber, an inclinedgrate arranged at the bottom of the chamber for supporting the charge, aradiant resistor carried by the body and arranged within the chambersome distance above the charge, a charging hopper formed in theupcharging hopper with the chamber, and means for admitting nitrogen gasinto the chamber. c

8. An electric furnace for the production of titanium-nitrogencompounds, comprising a refractory body forming a" chamber, arTin-"clined grate arranged at the bottom of the chamber for supporting thecharge, a radiant resistor carried by the body and arranged within thechamber some distance above the charge, and means for admitting nitrogeninto the charge.

9. An electric furnace for the production of titanium-nitrogencompounds, comprising a refractory body forming a chamber, an inclinedgrate arranged at the bottom of the chamber for supporting the charge, aradiant re s1stor carried by the body andarranged within the chambersome distance above the charge, and means for admitting nitrogen gaslntot the charge and immediately above the gra e.

v 1Q. An electric furnace for the production of titanium-nitrogencompounds, comprising a refractory body forming a chamber, an inclinedgrate arranged at the bottom of the chamber for Sig) orting the charge,a radiant resistor carrie y the body and arranged within the chambersome distance above the charge, and means for directing a flow ofnitrogen gas up through the charge.

'In' testimony whereof, we have hereunto signed our names.

FRANCIS A. J. FITZGERALD. JAMES KELLEHER.

per part of the body, a chute connecting the v

